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Nitrification in soils amended with AS and ALF was always significantly lower than in soils amended with US and LF. The same trend was reported in previous work by Fangueiro et al. (2010) using pig slurry, but the effect of acidification on nitrification was shorter. The nitrification in ALF amended soil remained similar or lower than in control. Hence, it may be hypothesized that acidification of the US and LF delays or inhibits the nitrification process in soil. Furthermore, it was shown here that this effect was more pronounced in ALF than AS treated soil. The effect on nitrification observed here after ALF application to soil is similar to those observed in soils treated with nitrification inhibitors (Fangueiro et al., 2009).
4. Conclusion Our results showed that the application to soil of acidified slurry or derived liquid fraction have a significant impact on the nitrification and N mineralization process since acidification significantly slow down nitrification. The potential as nitrification inhibitor may be considered as another benefit of slurry acidification since it may, indirectly, decrease nitrate leaching.
References Eriksen J., Sorensen P. And Elsgaard L. 2008. The fate of sulfate in acidified pig slurry during storage and following application to cropped soil. Journal of Environmental Quality 37, 280–286.
Fangueiro, D., Fernandes, A., Coutinho, J., Moreira, N. And Trindade, H. 2009. Influence of nitrification inhibitors on annual ryegrass yield and soil mineral N dynamics after incorporation with cattle slurry. Communications in Soil Science and Plant Analysis 40 (21), 3387-3398.
Fangueiro D., Ribeiro H., Coutinho J., Cardenas L., Trindade H., Cunha-Queda C., Vasconcelos E. And Cabral, F.
2010. Nitrogen mineralization and CO2 and N2O emissions in a sandy soil amended with original or acidified pig slurries or with the relative fractions. Biology and Fertility of Soils 46 (4), 383-391.
Plaza, C., García-Gil, J.C. and Polo A 2005. Dynamics and model fitting of nitrogen transformations in pig slurry amended soils. Communications in Soil Science and Plant Analysis 36, 2137–2152.
Sørensen P. and Eriksen J. 2009. Effects of slurry acidification with sulphuric acid combined with aeration on the turnover and plant availability of nitrogen. Agriculture Ecosystems and Environment 131, 240–246.
Nitrogen Workshop 2012
Nitrogen leaching and nitrous oxide emissions from grassland soils receiving dairy soiled water Minogue, D.a, French, P.b, Bolger, T.c, Murphy, P.N.C.d a Teagasc, Animal and Grassland Research and Innovation Centre, Grange, Co. Meath, Ireland b Teagasc, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland c School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland d Teagasc, Agricultural Catchments Programme, Johnstown Castle Environmental Research Centre, Co Wexford, Ireland
1. Background & Objectives Intensive dairy production is associated with high stocking rates and inputs of N in fertiliser and/or feed. Ireland has a national target of a 50 % increase in dairy production by 2020 which must be achieved while meeting environmental commitments in terms of water quality and greenhouse gas (GHG) emissions. Therefore, management strategies are required to maximise N use efficiency and minimise nitrate leaching and N2O emissions on dairy farms (Casey and Holden, 2005; Humphreys, 2008). Dairy soiled water (DSW) is an effluent produced on Irish dairy farms through the regular washing of milking parlours and holding areas and is typically spread on grassland throughout the year. It has a high N fertiliser replacement value (NFRV) (Minogue et al., 2011) and can be substituted for inorganic fertiliser N. Land application is likely to be associated with some risk of nitrate leaching and N2O emission and this is likely to vary with season of application and soil characteristics, such as drainage (moisture conditions). This work examined the effect of substituting DSW for fertiliser N at three different times of the year on N leaching and N2O emissions from two drainage-contrasted grassland soils.
2. Materials & Methods Nitrogen leaching and N2O emission from 32 undisturbed grassland soil monolith lysimeters (30 cm diameter x 70 cm depth), managed at a relatively high total N input of 198 kg ha-1 yr-1, was measured over a year. There were two soils (a well drained Acid Brown Earth and a poorly drained Gleysol) and four treatments (Table 1): a control receiving fertiliser N (FN) (calcium ammonium nitrate (CAN)) through the growing season at agronomic rates, and 3 treatments with soiled water substituted for fertiliser N (on a total N basis) at different time periods (May-August (DSW1), September-December (DSW2) and January-April (DSW3)). For the DSW treatments, DSW was applied at the legal maximum rate of 50,000 l ha-1 (33 kg N ha-1) every six weeks during the soiled water application period and fertiliser N was applied at agronomic rates at other times.
Concentrations and total fluxes of N were monitored in leachate and N2O emissions were monitored using the static chamber method, sampling 0, 1, 4, 7, 14, 21 and 28 days after the application date.
3. Results & Discussion Average annual N leachate loss from the well drained Acid Brown Earth (14.9 kg ha-1) was higher than from the poorly drained Gleysol (4.4 kg ha-1). Leachate N losses amounted to 7 % and 2 % of
applied N, respectively. Drier soil conditions, better aeration and resultant nitrification, and more rapid vertical transport, as evidenced by more rapid Br breakthrough, likely account for the greater leachate losses from the Brown Earth. Despite the contrasting soil type and drainage conditions, however, total annual N2O emission was not significantly different, at 4.97 and 6.11 kg N ha-1, for the Brown Earth and Gleysol, respectively, suggesting that N2O emission may not be as sensitive to soil type as might have been expected. Despite the increased hydrological load with DSW applications, leachate N loss for FN (12.0 kg ha-1) was higher than for DSW1 (6.8 kg ha-1) and DSW3 (7.5 kg ha-1), but was not significantly different from DSW2 (12.2 kg ha-1). Similarly, annual N2O-N emissions were lower for DSW1 (4.0 kg ha-1) and DSW3 (3.9 kg ha-1) than DSW2 (8.0 kg ha-1) or FN (6.4 kg ha-1). Results suggest that substituting DSW for fertiliser N during the growing season (Spring to Summer) may decrease nitrate leaching by 37-43 % and N2O emissions by 37-39 %. This may be due to the form in which N is applied in DSW; roughly two thirds as organic N and the balance largely as NH4-N. In contrast, N in CAN is composed of 50 % NH4-N and 50 % NO3-N. Therefore, N applied in CAN may be more susceptible to leaching and also to nitrification and denitrification and resultant N2O emission.
a a a 8 Total N leachate loss (kg N/ha)
4. Conclusion Substituting DSW for fertilizer N during the growing season (Spring to Summer) may decrease nitrate leaching by 37-43 % and N2O emissions by 37-39 %, possibly due to a lower susceptibility to leaching and N2O emission of the organic N in DSW compared fertiliser N. This presents an opportunity to decrease fertiliser N use and costs, increase N use efficiency and decrease N leaching and GHG emissions on dairy farms through improved management of DSW. Due to the high NFRV of DSW, this may be done while maintaining the same level of grass growth. As might be expected, leachate losses of N are likely to be higher on more free-draining soils, but N2O emission may not be as sensitive to soil drainage characteristics.
References Casey J.W. and Holden N.M. 2005. The Relationship between Greenhouse Gas Emissions and the Intensity of Milk Production in Ireland. Journal of Environmental Quality 34, 429-436.
Humphreys J. 2008. Nutrient issues on Irish farms and solutions to lower losses. International Journal of Dairy Technology 61, 36-42.
Minogue D., French P., Bolger T. and Murphy P. 2011. The fertiliser potential of dairy soiled water in temperate grasslands. Agricultural Research Forum 2011, Tullamore, Ireland, 8.
Nitrogen Workshop 2012
Nitrogen use efficiency improvement in heavy-pig production in Northern Italy Della Casa, G.a, Pacchioli, M. T.b, Marchetti, R.a a Agricultural Research Council CRA, Research unit for pig husbandry, Modena, Italy b Research Centre on Animal Production – CRPA, Reggio Emilia, Italy
1. Background & Objectives Italian livestock sector is concentrated in 5 regions of Northern Italy where about 70% of cattle, 85% of pigs (7.5 millions) and 80% of poultry are reared in intensively cultivated and inhabited areas. Protecting water bodies from nutrient pollution, as well as reducing odours from livestock in populated areas, represent very important issues of research and demonstration activities related to animal science in Italy. The Italian pig production chain is based on heavy pigs (160 kg and 9month old) intended for industrial processing. During the finishing stage (80 to 160 kg live weight) the quantities of feed (soybean meal/corn based diet) supplied are limited, to slow down the animal growth rates. During this phase it is common practice to use diets containing 0.7-0.6% lysine and 14% crude protein.
The research project “Feeding techniques for the reduction of the environmental impact of N in Italian intensive farms” (RENAI) has studied how to reduce protein content in the heavy-pig diet in order to obtain a significant reduction in in the manure N content and ammonia emissions, without impairing productivity levels. The diets with reduced protein content were integrated with synthetic amino acids, in order to ensure the same essential-amino acid supply.
3. Results & Discussion In the first trial (Table 2) a small decrease in A.D.G. was observed (P0.01) in the low-protein diet, due to a weight gain reduction during the first 28 trial days; in the second trial the kind of diet did not impair both in vivo and slaughtering performances. In both trials the low-protein diet gave rise to a decrease in N excretion and an improvement in yield of the ingested N (Table 2).
Ammonia emissions were also reduced (data not showed) in both trials. A reduction in slurry produced from animals fed different diets was also observed in both trials due to a reduction of voluntary water intake. A wide international literature shows that by lowering crude protein in the diet it is possible to obtain a reduction in N excretion in pigs slaughtered at 100-120 kg (e.g.
Aarnink and Verstegen, 2007); in the heavy pig Piva et al. (1996) showed that the ingesta-excreta N balance may be improved by reducing dietary crude protein. In our trial a protein reduction did not impair the pig performances except for a A.D.G. reduction in the first trial probably due to an abrupt change of crude protein level at the start of the trial.
4. Conclusion There is scope for improvement in use efficiency of' N from feed in the Italian production of heavy pigs. Results from these trials will be used to scale up the systems at demonstrative level in the LIFE+ Project AQUA. coordinated by CRPA (http://aqua.crpa.it).
References Aarnink, A. J. A. and Verstegen, M. W. A. 2007. Nutrition, key factor to reduce environmental load from pig production. Livestock Science 109:194-203.
Piva, G., Morlacchini, M., Prandini, A. and Fiorentini L.1996. Performance and nitrogen balance in pigs fed with four ideal protein diets. In: Proceedings of the 14th IPVS Congress, 7–10 July, Bologna, Italy, p.417.
Nitrogen Workshop 2012
Nitrogen use efficiency on dairy farms Mihailescu, E.a,b, Murphy, P c, Casey, I.A.b, Humphreys, J.a a Teagasc, Animal &Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Rep. of Ireland b Department of Chemical and Life Sciences, Waterford Institute of Technology, Cork road campus, Waterford, Co. Waterford, Rep. of Ireland c Teagasc, Johnstown Castle, Co. Wexford, Rep. of Ireland
1. Background & Objectives The Nitrates Directive regulations were implemented in August 2006 in Ireland under Statutory Instrument (SI) 378. These regulations limit the stocking densities and curtail the use of nitrogen (N) on farms. The objective of this study was to examine N balances and N use efficiencies on dairy farms following the implementation of the nitrates regulations under statutory instruments (SI 378, 2006; SI 101, 2009; SI 610, 2010).
2. Materials & Methods Twenty-one dairy farms located in the south and east of Ireland were surveyed on a monthly basis during year 2010. Stocking density was expressed as the quantity of N excreted by livestock using standard values from the SI relative to the area of the farm used for agricultural production. The N imports (chemical fertiliser, purchased concentrates, silage and livestock) and N exports (milk, livestock and silage sales) passing the farm-gate were quantified. Nitrogen imported in concentrate feed onto farms was calculated by multiplying the total quantity of concentrate fed by its protein concentration divided by 6.25. The N content of imported and exported silage was calculated by dividing its protein concentration by 6.25 (McDonald et al., 1995). Nitrogen in milk exported from farms was calculated by dividing milk protein concentration by 6.39. Nitrogen exported in livestock leaving the farms was calculated by estimating the total live weight of the livestock sold (or died) from the farms and multiplying by 0.029 for calves and 0.024 for older animals (ARC, 1994). All N imports and N exports were expressed relative to the utilised agricultural area. The farm-gate balance was the difference between N imports and N exports, whereas N use efficiency was calculated as the ratio between N exports and N imports.
3. Results & Discussion The mean stocking rate was equivalent to 183 kg ha-1 (s.d. 31.6) of organic N. Dairy livestock was 72% of total livestock on farms. The farm-gate balance (kg N ha-1) ranged from 73 to 285 with a mean of 196 (s.d. 62.6). Nitrogen use efficiency ranged from 16% to 43% with a mean of 28% (s.d.